Sean O'Brien insists Ireland would have known exactly what to do if faced with Italy's no-ruck tactics that bamboozled England on Sunday.

Italy's refusal to ruck at Twickenham caught England cold, with the hosts forced to overturn a 10-5 half-time deficit for their eventual 36-15 victory.

England boss Eddie Jones slammed the approach, but the brainchild of defence coach Brendan Venter has received as much acclaim as critique.

Leinster flanker O'Brien praised Italy's savvy ruse then admitted Ireland were aware that no ruck means no offside line - and would have known straight away how to combat it.

Asked if Ireland would have had an immediate answer to Italy's ploy dubbed 'The Fox' by boss Conor O'Shea, O'Brien replied: "Yeah, absolutely, up the jumpers stuff!

"I certainly would have known the rules around it anyway, England dealt with it in the end but in fairness to the Italians they were very clever and smart in the way they went about their game plan.

"So you have to hand it to them too, but you have to adapt to those situations if they arise and it took England a little bit to do that. But they got the result they needed in the end."

England's eventual bonus-point win over the Azzurri edges them ever closer to a title-decider against Ireland in Dublin on Saturday, March 18.

Ireland must first topple Wales in Cardiff on Friday, March 10 to set up a winner-takes-all showdown at the Aviva Stadium though, with O'Brien expecting a stern examination at the Principality Stadium.

Ulster centre Jared Payne could make a surprise Ireland return against Wales after shaking off his long-term kidney problem faster than expected.

England could claim a second successive Grand Slam and set a world-record 19 consecutive victories by seeing off both Scotland and Ireland.

Ireland boss Joe Schmidt has admitted the tournament closer against England will lose some shine if both teams are not contesting the title, but the hosts will doubtless be desperate to derail Jones' side whatever the shake-up.

England have already copped some criticism for failing to react quicker to Italy's ruckless wonders, least of all from referee Romain Poite.

The Frenchman told James Haskell "I can't say, I'm the referee, not a coach," when the Wasps flanker asked how England could coerce Italy to ruck.

Ireland have previously refused to engage in lineout mauls to fine effect under Joe Schmidt, and O'Brien's solution to England's Italy conundrum would have been to produce a series of pick-and-go drives to clear the Azzurri's blocking tactics.

"Once you're prepared properly for situations like that then it can work in your favour too," said O'Brien.

"You have to be on your toes in situations like that and get everyone on the same page quickly.

"They caught them on the hop, probably, and it's one of those things.

"There's a free-flow effect; the Italians weren't putting anyone into the breakdown and once they got a bit of momentum they were in the game straight away.

"So that's what kept them in it until half-time but, as I said, England did the job in the end."